A variety of methods and systems and methods exist to treat tissue, including mechanical means, lasers and other photon-based sources, radio frequency (RF) electrical currents, microwaves, cryogenic based techniques, and their various combinations, among others.
Each of these modalities has limitations which prevent a high degree of spatial control and precision during treatment. For example, in tissue the extreme absorption and scattering of photons relegates light based therapies to superficial applications that are tissue specific. Typically, electric currents, such as those emitted from a RF source, flow along the path of least impedance and are diffuse and non-selective, with maximum effect to tissue at the source. Further, the centimeter wavelengths of microwaves preclude tight focusing and energy placement in tissue.
Ultrasound can provide depth and precision of energy placement in tissue; however, it has currently been limited in application to either broad planar sources such as used in physiotherapy treatment, or as a single beam of focused sound, which is scanned sequentially over numerous areas, either electronically or mechanically, which is slow. Array based systems which can produce multiple sound beams are cumbersome and expensive and cannot in general produce output energy with a high degree of control or flexibility.
What is needed is an ultrasound treatment method and system that can provide simultaneous multiple beams of controlled energy to produce fractionated intense energy effects, such as thermal effects.